US2487818A

US2487818A - Antitank mine

Info

Publication number: US2487818A
Application number: US622916A
Authority: US
Inventors: Charles H Macfarland
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-10-17
Filing date: 1945-10-17
Publication date: 1949-11-15
Anticipated expiration: 1966-11-15

Description

'Nava 15;, 1949 I c. H. MacFARLANb ANTITANK MINE Filed Oct. 17, 1945 Patented Nov. 15, 1.949

UNITED STATES GFFICE Claims.

l The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to land mines.

A purpose of the invention is to provide a land mine the pressure plate of which will not be actuated by ground shock or air Waves resulting from explosions near the mine, but only by actual mechanical pressure from a passing vehicle or the like.

Another purpose of the invention is to provide a land mine which reduces the tendency for dirt, and gravel to obstruct the efficient functioning of the mine.

A further purpose of the invention is to provide an improved land mine which may be made of non-metallic materials.

Other purposes and advantages of the invention will become apparent from the following description of a preferred embodiment of the invention and which is illustrated in the accompanying drawings, in which:

Figure 1 is a plan view of the improved land mine, partly broken out;

Figure 2 is a fragmentary sectional view taken along line 2-2 of Figure 1, and

Figure 3 is a fragmentary sectional view taken along line 3-3 of Figure 1.

In the employment of explosive land mines intended for causing damage toor for destruction of hostile vehicles such as tanks, armored cars, mobile artillery and materiel and personnel carriers, it has been found that explosion of a single mine in a mine neld may, by such effects as sympathetic detonatlon or the force of the air set in motion by the explosive blast, cause one or more nearby mines to explode.

Thus the sudden increase in air pressure may depress the pressure plate or spider on a nearby mine, causing it to explode and in turn possibly exploding other mines, the result being the possible destruction of a Whole mine field or considerable portion thereof in consequence of merely exploding one mine in the iield. This invention is intended for preventing the above mentioned explosion of nearby mines by depression 0f their pressure plates or spiders as a result of a pressure wave caused by explosion of a nearby mme.

To this end, means are provided whereby a relatively even pressure over the surface of the pressure plate, such as may be caused by a sudden increase in air pressure, will not set off the mine and in which it is necessary for pressure to be amended April 30, 1928; 370 0. G. 757) applied to only a portion of the rim of the mine to actuate it.

As illustrated, the mine comprises a hollow casing or mine housing 2 which is preferably made of a molded phenolic plastic material or other suitable material. The housing 2 is closed at the bottom by a base disk 4 which may be made of resin bonded plywood or other suitable material. As seen in Fig. 2, matching circular grooves 6 and 8, half-round in cross section, are formed in the abutting surfaces of housing 2 and base disk 4 and in the annular space formed when the matching grooves 6 and 8 are aligned with each other is located an annular seal ring I0 made of rubber or other suitable material for effecting a water-tight joint between members 2 and 4. The joint may also be cemented if desired.

A charge I2 of 'INT or other suitable high explosive material is located inside the mine in the explosive chamber I4 formed between the inside wall of casing 2 and the base disk 4. A booster charge I6 is located in a booster charge chamber I8 formed in and surrounded by the charge I2. The booster charge chamber I8 has a central opening 0r fuse chamber 20 formed therein in which is disposed a mine fuse 22 having a cylindrical side wall 23 made of molded phenolic plastic material. The fuse 22 may be a chemical type fuse of the kind in which a sealed glass or plastic vial or ampoule 24 containing liquid sulphuric acid is disposed above a dry mixture 2E of potassium chlorate and sugar. When the vial 24 is broken, the released acid flows to and comes in contact with the mixture 26, causing it to burst into flame which ignites and explodes the heat sensitive explosive 28, located next to or just below the mixture 26 and which in turn explodes the surrounding annular shaped explosive booster charge 3D. The resulting iiame and blast passes through vent holes 32 formed in side wall 23, into contact with booster charge I6, exploding it and resulting in the explosion of the main TNT charge I2. As illustrated, the charge 30 is annular in shape and has a central bore 34 in which is disposed a cylindrical housing 36 rounded at its lower end 31 and containing the mixture 2G and the explosive 28, all the mixtures and explosives being sufciently separated from each other by being surrounded by or enclosed in suitable materials such as are well known in the art.

The fuse 22 is closed at its lower end by a hollow elongated plug 38 which is threaded at 4I) into an annular base member 42 which in turn is threaded at 44 into the lower end of the fuse side wall 23. The plug 38 has a hollow upward projecting portion 46, closed at its upper end 48 so that a cylindrical recess 50, threaded at 5| and open at the bottom 52 is provided, and into which an anti-lift or pull type fuse may be inserted in any usual manner for causing the mine to explode if lifted. The members 38 and 42 are preferably made of plastic materialor other-'suitable nonmetallic material. Ase'alwasher isvlocate'dat53 as shown.

The fuse 22 is closed at its upper end by horizontal top wall 54 which is thicker thanthe side walls of the fuse. A horizontal cylinfdrical recess 56 is formed in top Walli541toreceivesthev ampoule 24, a plug 58 being threaded into the open end of the recess 56 to closeit Feltpa'cking' 60 packed around the ampoule 24 serves to protect the ampoule against breakage due to looseness in the recess 56.

The mine has a pressure platee Milformett" or" Y ceramic or plastic material. The pressure plate B/Zfi'ssubstantially;icircularrirrplan View as shownin Figure 1, and has its central topvsurilacezrat: ask at V:Ii-4 andrthef :remaining -rim portion formed with anfannularholmw depression inrits:y upper surface as-at. @6eme-outer edgeff fof-.the rim. havingv its top :surface-09 j`coplianar` with theffcentralfsurface llt-fofwthe-Y pressrrrevplate. Asv best seen in :Figures-f 2 andtthe minfecasing;` 2-has` an l annular upstanding elevatedyportion orbead; 'HIs upon which is vsupportedtlfre.lowermost portion: of..- the: underside-of theA depressed portion :66-V of the'. rim as atv 12. Itswill.L thusA 'be noted vthat downward pressure at-iany pointrorrthe outer. edge-iii!!V Off the. rimv asi-nA .theedirection ofsthe; arrow 'Mein Figure-f2; will beznecessaryrvto-tiltethe pressure`v plate, in which vcase-the bead-'Nr will servevas-the` fulcrum, andfthecentralportion.640iV the pressure plate will risessu'bstantiall-y in theedireetion of .the arrow.- Ss-hown inFigure 2.:

To-cause pressure ornapoint :on the-rimasat- 'I4 .to break theglass-ampoule 24 thereby-liberating.v its contents and setting foi.. the4 mine,v an.. ampoule breaking; member` T8; ispro-vided` as. shown in yligures -2 landpr Thesmember. '|8` has-rI an upper substantially cylindrical uportion Illpand.- 4 a lower ring. ylike portion E'Z'as best seen;finfl'igure.V 3,. the lower portion havingsa transverse aperturef 84 therethrough, through `which. theampouIe. fllextends` and which ,thusenci-'rcles .the ampoule;- with a l small amount. of; clearance .between the.. outer,A ampoule.. surface and lth'einner surface. ofi.' the hole 811i The topportion ofthefuse 22"? has an appropriate vertical aperture formed'.. therethrough to allowthe l'wer4 portionLZJto `extend'into Ithe hole 86 withcle'arancearound iti.. The Vuma-er portion. illfof ampoulebreaking" memloerVr "Is" extends through' ai vertical. cylindrical' aperture 83 tnepressure plate, tne'faperture' 8827 being enlarged' at 901'! A Y snap j ringLj9T'di'sp1sedj partly in' an annular peripheral' groove 94V on', portion 80'; servesVK tozprevent the member' lifroml moving further downward :ntolole Vanolpitcl'f or other. sealingmateiial 'located in` tl"1"'e"1sur`4 j rounding space, serves botlras :a seal andY for-pre-` venting upward nrotioni ofrr'ieihl'aer 8^`apartl fr'or'n'- the pressure plate., s,

As seen in Figures Zand vthe-pressureepl'ate has a downwardly?projecting.hollow cylilnzl'ricalll extension 98, large enoughlin-insidediameterto. lit over` the upper.. portiorr 54. of tfuse-222.A with. adequate clearance,- `the extension-havingaexternai lthreads ate-|001 Af-snfaplrsprin-ge|02srmade ofi phenolic plastick or" other suitable? materiah. has@ a. central hollow cylindrical portion or: hub |041' plate. The snap spring 02 also has six spaced ngers |06 radiating from its cylindrical hub |04 as best seen in Figures 1 and 2, the distal ends |08 of the ngers |06 being receivable in an annular notch ||0 formed in the upper surface of casing 2 under the inner side 1I of bead |0 as shown in Figure Toyallfow-the six radiating. fingersA |06`f of the spring |02 to enter the notch ||0, the overhanging portion |I of the bead l0 is cut away as shown in Figure 3 at six corresponding spaced intervals indicated at 2 in Figure 1, thus leaving the overhanging. portions of the bead 10 only between the six cut away intervals |2. Thus, t0

. the end lofeeach springnger'llllinthenotch cannot take anypermanent set. The snapacti'on" Llargev clearance hole is' provi'ded"'i'r the' yoke'soi' nopload-whatever is puton the ampouletuntil'i the snapfspring: releases; This'means thatvl theV load 'required 'to"break theampoule. need not" bev` considered. in computin'gj the` rim load1 at which" theY mineA operates; Phen'olicwmaterial laminated with kraftf paper is* recommended as'suitable for* use in makingthe spring' 025 Y e A cylindrical rubber sealingA bellows I has* annular beads` ||8 and` |2'0"'adapter?f'or-loieine snapped Afinto-correspohd'i ng annularfgrooves: |22

10, the holes vbeingjspar-:ed byIzodegre'esfromr ,each other and .locatedN within the" pjortionsf I2 of the bead 'I' Y Correspondingjunthreaded"holes-' I 30"' are' formed/through'. the'abutting depressed portion ofthe'pressureplatel' Whenthe holesf* are in registry with .thejholes v|28;tlil'lrnlrscrewsi'i preventing the; pressure.; plate" from tilting and 'j ezq'aIc'ding.the'mine-v To armi the mine it' ispnlyii necessary to remove the thumb' screws |321 For, nal assembly, ,the fuse. assembly. isfrst consisting,V ofthee chemical fuse.

assembled, boosterpellet, primer mixture, upper aridlower-v detori-atorvclfrarges; andampoule. LW all moan-tedI ff threaded: to: the f extension 98 eY or: the: pressure? 751 inthe plslfisylndel'f threaded atf thefbtiiomf;

end as already explained, and the yoke 18, fitting loosely over the center of the ampoule in the slot 88 at the top end of the plastic cylinder. The fuse assembly is inserted into the proper cavity in the body portion and xed in place by turning up the bottom center plug 38. This plug contains a cavity into which an anti-lift fuse may be inserted in the usual manner.

The next step is to place the top sub-assembly comprising the pressure plate and snap spring over the mine casing, centered so that the fingers |06 of the plastic spring will drop down to the level of the notch Hi8, being in positions H2.

VVThe top sub-assembly is thenrrotated one-twelfth of a turn to bring the spring fingers E05 into positions H4. This also results in aligning the thumb screw holes for insertion of the thumb screws.

Sealing of the mine is next accomplished by snapping the rubber seal bellows IE5 into positions as shown in Figure 2. The iinal operation Consists of installing the snap ring 92 over the top of the yoke into groove 94, and sealing the snap ring by filling the cavity around it with a plastic sealing compound.

While a preferred embodiment of the invention has been described in specific terms, it is to be understood that numerous changes may be made in the size, shape, materials, and arrangement without departing from the spirit and scope of the invention.

I claim:

1. A land mine comprising a hollow casing, an explosive charge in said casing, an annular upstanding ring carried on said casing, a circular pressure plate supported on said ring concentrically therewith, said plate having a substantially greater diameter than the ring, whereby unbalanced pressure on the thus overhanging rim of said pressure plate will cause the plate to pivot on the ring as a fulcrum thus elevating the center of the pressure plate, an annular hub concentrically secured to said pressure plate, a plurality of substantially arcuate spring arms radiating from said hub, interlocking means between the free ends of said spring arms and said annular upstanding ring, and primer means responsive to upward movement of any portion of the plate for igniting said explosive charge, said spring arms initially resisting such upward movement of the plate and then suddenly releasing such resistance upon said spring arms reaching a predetermined degree of stress.

2. In a land mine, a hollow casing having an external shape generally in the form of a segment oi a sphere and having a normally vertical central axis, an upstanding ring xed on said casing externally thereof and concentric of said axis, said ring being formed to provide a plurality of crcumferentially-spaced inwardly-facing notches about the periphery thereof, a circular pressure plate of greater diameter than said ring, means securing said pressure plate to said casing in position resting on said ring, said means comprising a Belleville-type spring centrally secured to said pressure plate at the central under portion thereofV and having radial arms whose ends engage in respective ones of said notches, and means responsive to upward movement of the center of said pressure plate as a result of downward pressure upon the rim thereof, to detonate a fuse in said casing, said spring acting to resist the upward movement aforesaid.

3. A mine as recited in claim 2, the diameter of the base of said casing being approximately twice the diameter of said pressure plate.

4. A mine as recited in claim 2, and safety means comprising a plurality of removable screws rigidly connecting said pressure Vplate to said ring at points circumferentially spaced about the periphery thereof.

5. A mine as recited in claim 2, said lastnamed means comprising an ampoule mounted centrally in said casing closely adjacent said pressure plate, and a ring secured to said pressure plate centrally therebeneath and encircling said ampoule.

CHARLES H. MACFARLAND.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,539,609 Taylor May 26, 1925 2,336,701 Rasmussen Dec. 14, 1943 2,383,885 Parsons et al Aug. 28, 1945 FOREIGN PATENTS Number Country Date 46,380 Sweden Jan. 14, 1920 864,354 France 1941